With the development of memory systems including a memory device, the number of memory devices included in a single memory module or system has increased. Accordingly, the possibility of defects occurring in memory devices has also increased. Therefore, a test procedure for searching out and detecting defects has become important.
In general, in testing a memory device, data is written to memory cells in the memory device using an external test device, the data is read from the memory cells, and then the data that has been read is compared with the data that has been written to determine whether the memory device is good or bad. When the test device tests a plurality of memory devices included in a single memory module or a single memory system using particular data, the test device often needs to repeatedly perform a test on each of the memory devices since data lines connected between the test device and the memory devices are different. Therefore, a long test time is typically required.
Furthermore, when a memory module includes a plurality of memory devices and a memory controller controlling the memory devices, it is difficult for the memory controller to input predetermined data to a particular data line of a memory device.